Seasonal affective disorder (SAD), a recurrent fall-winter depression with periods of remission in spring and summer, is a highly prevalent mental health problem, especially at Northern latitudes. Although remission rates vary across studies, it is estimated that a significant minority (i.e., as many as 40-50% of SAD sufferers) is refractory to treatment with light therapy--the "gold standard" for SAD treatment. Alternative and/or supplementary treatments are needed. Cognitive-behavioral therapy (CBT) is effective for non-seasonal Major Depressive Disorder, but has not been adequately explored in the case of SAD. Our preliminary work suggests that individuals with SAD demonstrate a negative cognitive style, behavioral withdrawal, and rumination, and further research on cognitive-behavioral models for SAD is needed. Our pilot work further suggests that CBT, alone or combined with light, may be as effective as light alone in reducing acute SAD symptoms and may have more durable effects than light therapy into the subsequent winter season (Rohan et al., 2001; 2002). In an apparent synergistic effect, the combination of CBT and light therapy together produced superior remission rates to either treatment alone at post-treatment and at one-year follow-up. Two studies are proposed to explore cognitive-behavioral models and treatments for SAD. STUDY 1 expands our pilot study by increasing sample size, adding a control group, and employing a longer-term follow-up. It involves a comparison of light therapy, CBT, their combined "synergistic" effects, and a minimal contact/delayed treatment control in treating a current SAD episode over a six-week trial. Light therapy will be administered according to standard protocol. Manualized CBT will be conducted in groups, meeting twice a week. Indices of symptom severity and remission and relapse rates will be examined throughout the winter and during the summer. To examine the prophylactic value of these treatments, participants from our ongoing pilot study will be assessed for symptom severity and presence of a Major Depressive Episode during the winter (i.e., one year following treatment completion). STUDY 2 compares individuals with SAD, those with non-seasonal depression, and never-depressed controls on various cognitive-behavioral factors including automatic thoughts, dysfunctional attitudes, schemata, rumination, activity frequency and enjoyment, and reactivity to light-related stimuli. The proposed studies will contribute to the development of CBT approaches to SAD and to understanding interactions between biological and psychological factors in SAD symptomatology. [unreadable] [unreadable] [unreadable]